Electrical conducting phthalonitrile polymers

ABSTRACT

Compounds of the general formula: ##STR1## wherein R 1  is an isomer of phthalaldehyde; R 2  is an isomer of anromatic dialdehyde selected from the class consisting of phthalaldehyde, naphthalene dialdehyde, phenanthrene dialdehyde, anthracene dialdehyde, biphenyl dialdehyde, terphenyl dialdehyde; and mixtures thereof and R 3  is an isomer of an aromatic diamine selected from the class consisting of benzene diamine, naphthalene diamine, phenanthrene diamine, biphenyl diamine, and terphenyl diamine, and the cyano-condensation resins thereof which are useful in preparing semiconductors.

This is a division of application Ser. No. 681,087 filed on Apr. 28,1976, now U.S. Pat. No. 4,057,569.

BACKGROUND OF THE INVENTION

This invention pertains generally to organic polymers and in particularto organic semiconductors.

A semiconductor is a near insulator at room temperature. At thistemperature the resistivity of a semiconductor is from 10⁻² to 10⁺⁹ ohmcm.

Until recently organic polymers were generally considered to be verypoor conductors of electricity. Newly discovered organic polymers,however, have shown promise as semiconductors. These polymers have thedisadvantages of low molecular weight and poor moldability.

SUMMARY OF THE INVENTION

It is therefore an object of this invention to provide a class of highmolecular weight polymeric semiconductors which can be processed intoconvenient shapes by conventional resin technology.

Another object of this invention is to provide polymeric semiconductorswith low resistivity and high structural strength.

These and other objects are achieved by a heat-treated totallyconjugated cyano-condensation resin of bisorthodinitrile selected fromthe class consisting of ##STR2## wherein R₁ is an isomer ofphthalaldehyde; R₂ is an isomer of an aromatic dialdehyde selected fromthe class consisting of phthalaldehyde, naphthalene dialdehyde,phenanthrene dialdehyde, anthracene dialdehyde, biphenyl dialdehyde, andterphenyl dialdehyde; and R₃ is an isomer of an aromatic diamineselected from the class consisting of benzene diamine, naphthalenediamine, phenanthrene diamine, biphenyl diamine, and terphenyl diamine.Such high molecular weight totally conjugated resins provide excellentconductivity through the large number of π-electrons and by the absenceof a separation between the conjugate bonds.

DETAILED DESCRIPTION OF THE INVENTION

The bisorthodinitriles of the general formula: ##STR3## are prepared byreacting 4-aminophthalonitrile with the appropriate isomer ofphthalaldehyde in a refluxing solvent. The synthesis involvingp-phthalaldehyde proceeds accordingly: ##STR4##

The bisorthodinitriles of the general formula: ##STR5## are prepared byreacting 4-aminophthalaldehyde with an aldehydeterminated Shiff base(anil) of the general formula: R₂ ═R₃ ═R₂ in a refluxing solvent. Anexample of this synthesis is as follows: ##STR6##

The aldehyde-terminated Shiff base (anil) is prepared by condensing anaromatic diamine with an aromatic dialdehyde in an amount at least 5mole percent in excess of the stoichiometric amount. The reactants arediamines and dialdehydes of benzene, naphthalene, phenanthrene,anthracene, biphenyl and terphenyl. An example of the synthesis is:##STR7##

In order to decrease the reaction time for the synthesis of either ofthe general compounds of this invention, a stoichiometric excess of4-aminophthalonitrile is used. The preferred excess is from 5 to 15 molepercent of the stoichiometric amount, which is two moles of4-aminophthalonitrile for each mole of the aldehyde terminated reactant.The reactant time can be further reduced by the inclusion of a catalystsuch as p-toluenesulfonic acid monohydrate. The refluxing can be carriedout with any of the usual refluxing fluids. The most common fluids arepreferred, such as, toulene, chlorobenzene, and methyl phenyl ether(anisole). The end point of the reaction can be easily determined bymonitoring the by-product, water, or one of the reactants.

The general nature of the preparation of the bisorthodinitrile have beenset forth, the following examples are presented as specificillustrations thereof. It is understood that the invention is notlimited to these examples but is susceptible to different modificationsthat would recognized by one of ordinary skill in the art.

EXAMPLE I Preparation of Bis(3,4-dicyanoaniline) N,N'-p-xylylenediidene

A 2-liter flask was equipped with Dean and Stark distilling trap and awater-cooled condenser and then charged with p-phthalaldehyde (8.05 g;0106 mole), 4-aminophthalonitrile (18.90 g; 0.132 mole) and toluene (946ml). The stirred reaction mixture was refluxed 10 hours. At this point,water (2.0 ml) had collected in the distilling trap (theory, 2.16 ml).The heavy yellow precipitate from the cooled reaction mixture wascollected by filtration, washed with toluene (200 ml), and dried. Thisyellow residue was extracted with boiling acetonitrile (2 × 600 ml)leaving, after drying, 11.1 g of the analytical anil, mp 272°-275° C.Cooling the resulting filtrate to 0° C. deposited additional crystals,which were collected and dried to give 8.9 g more of the analyticalanil, mp 272°-275° C.; total yield 20.0 g (86.7%); Anal. calcd. for C₂₄H₁₂ N₆ : C, 74.99; H, 30.4; N, 21.86; Found: C, 74.94; H, 3.04; N,21.94. Note: The above anil can be recrystallized from anisole.

EXAMPLE II Catalyzed preparation of Bis(3,4-dicyanoaniline)N,N'-p-xylyenediidene

A 2-liter flask was equipped with Dean and Stark distilling trap and awater-cooled condenser and then charged with p-phthalaldehyde, (8.05 g;0.06 mole), 4-aminophthalonitrile (18.90 g; 0.06 mole),4-aminophthalonitrile (18.90 g; 0.132 mole) p-toluene-sulfonic acidmonohydrate (0.03 g.). The results were identical to Example I.

EXAMPLE III Preparation of Bis(3,4-dicyanoaniline) N,N'm-xylylenediidene

The corresponding m-isomer, i.e., bis(3,4-dicyanoaniline)N,N'-m-xylylenediidene was prepared in a similar way. The reactionchange was m-phthalaldehyde (4.80 g; 0.358 mole), 4-aminophthalinitrile(11.27 g; 0787 mole), 0.02 g p-toluenesulfonic acid monohydrate andtoluene (474 ml). Refluxing the reaction mixture for 4 hours removed 1.1ml of water (theory 1.3 ml). Filtration of the reaction mixture 60° C.)left a pale yellow residue after drying of 13.6 g, m.p. 253°-257° C.,98.9% yield, pure enough for most purposes. Recrystallion from anisoleor from a 50:50 volume mixture of toluene: pyridine leads to theanalytical m-dianil, m.p. 254°-258°:

EXAMPLE IV

Preparation of ##STR8##

A. Preparation of the aldehyde-terminated Shiff base (anil) ##STR9## Acharge of m-phenylenediamine (4.03 g; .0373 mole), p-phthalaldehyde(12.70 g; .0946 mole) and 1000 ml of toluene was stirred and refluxedusing a Dean and Stark water distillation trap. After 3 hours 1.00 ml ofwater was collected (1.34 ml theory). This gave the crude polymericaldehyde terminated anil. B. Preparation of the Bisorthodimitrile##STR10## To the reaction solution of part A 4-aminophthalanitrile(11.75 g; 0.0820 mole) was added, and stirring and refluxing wascontinued for 16 hours. An additional 1.20 ml of water accumulated inthe water trap. The hot reaction mixture (80° C.) was filtered to get13.4 g of yellow crystals (mp 225°-245° C.). To assure complete reactionthis residual was combined with 4.00 g of 4-aminophthalonitrile andtoluene (473 ml). Further refluxing and stirring led to the removal of0.1 ml water. Filtering at 80° C. left 10.0 of yellow crystals.Extraction with boiling acetonitrile (200 ml) left 8.07 g of yellowcrystals containing no NH₂ or CHO groups by(Infrared Spectroscopy), ,m.p. 235°-250° C.

A cyano-condensation resin of this invention is synthesized by simplyheating one of the aforedescribed bisorthodinitrile above the meltingpoint in an inert atmosphere, such as a vacuum from 1 to 10 mm Hg, oraragon, or nitrogen. The preferred temperature is from 1° to 30° C.above the melting point of the compound and the most preferred is from5° to 15° C. higher. Gelation generally occurs after 3 to 5 hours. Theheating is continued for at least another 20-25 hours in order to curethe product to a hard resin. The optimum cure time would have to bedetermined empirically for each resin. Prior to synthesis, it ispreferred that the bisorthodinitrile is outgassed by heating thematerial to a melt under a vacuum. The preferred vacuum is from 1 to 10mm Hg and the preferred time is from 15 to 20 minutes.

A cyano-condensation resin is also produced with the inclusion ofcertain metals and salts with the bisorthodinitrile. The inclusion of ametal or a metal salt causes the reaction to proceed quicker. Generallythe resins gel and cure from about 10 to 25 percent faster. The optimumcure for any particular resin is, of course, determined by the testingof structural strength of the resins samples over a range of cure times.The preferred amount of metal or metal salt is the stoichiometricamount, i.e., one at. wt. of metal or one mole of salt for each twomoles of bisorthodinitrile. If an excess of a metal or a salt,especially a salt is used, foaming results. Exemplary of metals whichmay be used are chromium, molybdenum, vanadium, beryllium, silver,mercury, aluminum, tin, lead, antimony, calcium, barium, manganese,magnesium, zinc, copper, iron, cobalt, nickel, palladium, and platinum.Mixtures of these metals may also be used. The preferred metals arecopper, silver, and iron.

Suitable metal salts include cuprous chloride, cuprous bromide, cuprouscyanide, cuprous ferricyanide, zinc chloride, zinc bromide, zinc iodide,zinc cyanide, ferrocyanide, zinc acetate, zinc sulfide, silver chloride,ferrous chloride, ferric chloride, ferrous ferricyanide, ferrouschloroplatinate, ferrous fluoride, ferrous sulfate, cobaltous chloride,cobaltic sulfate, cobaltous cyanide, nickel chloride, nickel cyanide,nickel sulfate, nickel carbonate, stannic chloride, stannous chloridehydrate, a complex of triphenylphosphine oxide and stannous chloride(2TPPO/SnCl₂) and mixtures thereof. The preferred salts are cuprouschloride, stannic chloride, stannous chloride hydrate, and ferrousfluoride. The cyano-condensation resins formed with metal salts have thedisadvantage of air spaces in the resin caused by foaming during thepreparation. As a consequence resins with a metal salts are not asimportant as the plain resins or the resins with a metal.

In summary the preparation of cyano-condensation resins with a metal ora salt comprises mixing a bisorthodinitrile with a salt or metal,outgassing the mixture as previously described, and heating the mixtureto a temperature above the melting point of the bisorthodinitrile. Thepreferred and most preferred temperatures are the same as those for thesyntheses without metal or salts. Since the salt or metal becomes partof the cyano-condensation resin, decreasing the particle size provides amore efficient utilization of the salt or metal. Thus particle sizes upto 2000 μ are preferred. The preferred amount of the salt or metal isthe stoichiometric amount.

The following examples are given to illustrate the preparation of thecyano-condensation resins of this invention and are not intended to thelimit the specification or the claims to follow:

EXAMPLE V Preparation of the Cyano-Condensation Resin fromBis(3,4-dicyanoaniline) N,N'-p-xylylenediidene

A 1-gram sample of the above bisorthodinitrile, prepared according tothe method of Example II, was heated at 270° C. for 24 hours. A harddark brown resinous material resulted.

EXAMPLE VI Preparation of the Cyano-Condensation Resin fromBis(3,4-dicyanoaniline) N,N'-p-xylylenediidene and copper

A 1-gram sample of the above bisorthodinitrile, prepared according tothe method of Example II was mixed with activated copper powder in adinitrile-to-copper mole ratio of 1:2. The mixture was heated at 270° C.for 18 hours. A hard dark brown resinous material was formed.

EXAMPLE VII Preparation of the Cyano-Condensation Resin from ##STR11##

A 1-gram sample of the bisorthodinitrile, prepared in Example IV washeated at 270° C. for 24 hours. A hard dark brown resinous material wasformed.

The examples show that a brown colored resin is formed. It is on accountof the brown color rather than a green color that it is believed that aphthalocyanine resin is not formed. The exact chemical identity of theresin is not known other than the resin is a cyano-condensationcompound.

After cure, the resin is heated further at a temperature from 350° to500° C. for at least 12 hours and preferably for 18 hours, in an inertatmosphere, e.g., argon, a vacuum, or nitrogen. This last heat treatmentgreatly improves the electrical conductivity of the resin, but doescause a slight weight loss.

Samples of the bisorthodintrile of Example I were mixed with copperflake and cured according to the method of Example VI. The samples werethen given a final cure for 18 hours at the specified temperature. Theconductivities of these resins are listed in Table I. As is shown inTable I, the best results are achieved with a stoichiometric amount ofcopper and high final cure temperature.

                  Table I                                                         ______________________________________                                                  Cu/BODN    Final Cure Condutivity                                   Sample No.                                                                              Mole Ratio Temp., ° C                                                                        ohm-con                                       ______________________________________                                        1         1/1        300        7.10.sup.8                                    2         1/1        450        7.9 × 10.sup.8                          3         1/2        450        5.4 × 10.sup.7                          ______________________________________                                    

Obviously many modifications and variations of the present invention arepossible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed and desired to be secured by Letters Patent of theUnited States is:
 1. A cyano-condensation resin obtained by heating oneor more bisorthodinitriles of the general formula ##STR12## wherein R₂is an isomer of an aromatic dialdehyde selected from the classconsisting of phthalaldehyde, napthalene dialdehyde, phenanthrenedialdehyde, anthracene dialdehyde, diphenyl dialdehyde and terphenyldialdehyde; and R₃ is an isomer of an aromatic diamine selected from theclass consisting of benzene diamine, napthalene diamine, phenanthrenediamine, biphenyl diamine, terphenyl diamine to a temperature above themelting point thereof.
 2. The cyano-condensation resin obtained byheating one or more bisorthodinitriles of claim 1 above the meltingpoint thereof.
 3. The cyano-condensation resin obtained by heating oneor more bisorthodinitrile of claim 1 above the melting point thereof. 4.The cyano-condensation resin obtained by mixing one or morebisorthodinitriles of claim 1 with a metal selected from the classconsisting of chromium, molybdenum, vanadium beryllium, silver, mercury,aluminum, tin, lead, antimony, calcium, barium, manganese, magnesium,zinc, copper, iron, cobalt, nickel, palladium, and platinum and heatingsaid mixture above the melting point of said bisorthodinitriles.
 5. Thecyano-condensation resin of claim 4 wherein said metal is selected fromsaid class consisting of copper, silver, and aluminum.
 6. Thecyano-condensation resin obtained by mixing one or morebisorthodinitrile of claim 1 with a salt from the class consisting ofcuprous chloride, cuprous bromide, cuprous cyanide, cuprousferricyanide, zinc chloride, zinc bromide, zinc iodide, zinc cyanide,ferricyanide, zinc acetate, zinc sulfide, silver chloride, ferrouschloride, ferric chloride, ferrous ferricyanide, ferrouschloroplatinate, ferrous fluoride, ferrous sulfate, cobaltous chloride,cobaltic sulfate, cobaltous cyanide, nickel chloride, nickel cyanide,nickel sulfate, nickel carbonate, stannic chloride, stannous chloridehydrate, a complex of triphenylophosphine oxide and stannous chloride(2TPPO/SnCl₂) and heating said mixture above the melting point of saidbisorthodinitrile.
 7. The semiconductor resin obtained by heating thecyano-condensation resin of claim 1 to a temperature from 350° C to 500°C for at least 12 hours in an inert atmosphere.
 8. The semiconductingresin obtained by heating the cyano-condensation resin of claim 4 at atemperature from 350° C 500° C for at least 12 hours in an inertatmosphere.
 9. The semiconducting resin obtained by heating thecyano-condensation resin of claim 6 at a temperature from 350° C to 500°C for at least 12 hours in an inert atmosphere.